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.Dd January 23, 2025
.Dt GCONCAT 8
.Os
.Sh NAME
.Nm gconcat
.Nd "disk concatenation control utility"
.Sh SYNOPSIS
.Nm
.Cm create
.Op Fl v
.Ar name
.Ar prov ...
.Nm
.Cm destroy
.Op Fl fv
.Ar name ...
.Nm
.Cm label
.Op Fl hv
.Ar name
.Ar prov ...
.Nm
.Cm append
.Op Fl hv
.Ar name
.Ar prov
.Nm
.Cm stop
.Op Fl fv
.Ar name ...
.Nm
.Cm clear
.Op Fl v
.Ar prov ...
.Nm
.Cm dump
.Ar prov ...
.Nm
.Cm list
.Nm
.Cm status
.Nm
.Cm load
.Nm
.Cm unload
.Sh DESCRIPTION
The
.Nm
utility is used for device concatenation configuration.
The concatenation can be configured using two different methods:
.Dq manual
or
.Dq automatic .
When using the
.Dq manual
method, no metadata are stored on the devices, so the concatenated
device has to be configured by hand every time it is needed.
The
.Dq automatic
method uses on-disk metadata to detect devices.
Once devices are labeled, they will be automatically detected and
configured.
.Pp
The first argument to
.Nm
indicates an action to be performed:
.Bl -tag -width ".Cm destroy"
.It Cm create
Concatenate the given devices with specified
.Ar name .
This is the
.Dq manual
method.
The kernel module
.Pa geom_concat.ko
will be loaded if it is not loaded already.
.It Cm label
Concatenate the given devices with the specified
.Ar name .
This is the
.Dq automatic
method, where metadata are stored in every device's last sector.
The kernel module
.Pa geom_concat.ko
will be loaded if it is not loaded already.
.Pp
Additional options include:
.Bl -tag -width ".Fl h"
.It Fl h
Hardcode providers' names in metadata.
.El
.It Cm append
Append a new device to the end of an existing concatenate device
with the specified
.Ar name .
.Pp
If the existing device is using the
.Dq manual
method, the new device is simply appended as-is.
.Pp
If the existing device is using the
.Dq automatic
method, the device is appended persistently.
New
.Cm gconcat
metadata is written to all existing components, as well as to the
newly added one.
.Pp
Additional options include:
.Bl -tag -width ".Fl h"
.It Fl h
Hardcode providers' names in metadata.
.El
.It Cm stop
Turn off existing concatenate device by its
.Ar name .
This command does not touch on-disk metadata!
.Pp
Additional options include:
.Bl -tag -width ".Fl f"
.It Fl f
Stop the given device even if it is opened.
.El
.It Cm destroy
Same as
.Cm stop .
.It Cm clear
Clear metadata on the given devices.
.It Cm dump
Dump metadata stored on the given devices.
.It Cm list
See
.Xr geom 8 .
.It Cm status
See
.Xr geom 8 .
.It Cm load
See
.Xr geom 8 .
.It Cm unload
See
.Xr geom 8 .
.El
.Pp
Additional options:
.Bl -tag -width indent
.It Fl v
Be more verbose.
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
variables can be used to control the behavior of the
.Nm CONCAT
GEOM class.
The default value is shown next to each variable.
.Bl -tag -width indent
.It Va kern.geom.concat.debug : No 0
Debug level of the
.Nm CONCAT
GEOM class.
This can be set to a number between 0 and 3 inclusive.
If set to 0 minimal debug information is printed, and if set to 3 the
maximum amount of debug information is printed.
.El
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.
.Sh EXAMPLES
The following example shows how to configure four disks for automatic
concatenation, create a file system on it, and mount it:
.Bd -literal -offset indent
gconcat label -v data /dev/da0 /dev/da1 /dev/da2 /dev/da3
newfs /dev/concat/data
mount /dev/concat/data /mnt
[...]
umount /mnt
gconcat stop data
gconcat unload
.Ed
.Pp
Configure concatenated provider on one disk only.
Create file system.
Add two more disks and extend existing file system.
.Bd -literal -offset indent
gconcat label data /dev/da0
newfs /dev/concat/data
gconcat label data /dev/da0 /dev/da1 /dev/da2
growfs /dev/concat/data
.Ed
.Sh SEE ALSO
.Xr geom 4 ,
.Xr loader.conf 5 ,
.Xr geom 8 ,
.Xr growfs 8 ,
.Xr mount 8 ,
.Xr newfs 8 ,
.Xr sysctl 8 ,
.Xr umount 8
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 5.3 .
.Sh AUTHORS
.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org
